1. Field of Invention
The present invention relates to an electronic timepiece with an internal antenna enabling receiving external radio frequency signals through the antenna.
2. Description of Related Art
Electronic timepieces with an internal antenna are known from the literature. Typical of such timepieces is a radio-controlled timepiece that receives external radio frequency signals carrying time information from an external source and uses this information to adjust the time kept by the timepiece. In order to improve antenna performance in this type of electronic timepiece with an internal antenna, Japanese Unexamined Patent Appl. Pub. JP-A-2005-269234 and Japanese Unexamined Patent Appl. Pub. JP-A-2007-184894 teach configurations that improve the flux collection effect of the antenna.
The wristwatch described in Japanese Unexamined Patent Appl. Pub. JP-A-2005-269234 has an internal antenna that includes a laminated core part, a winding part having a wire wound around the laminated core, and end caps affixed to both ends of the laminated core part.
The wristwatch described in Japanese Unexamined Patent Appl. Pub. JP-A-2007-184894 uses a configuration having a core, a core case housing the core, a coil wound around the core case, and an amorphous thin film applied to a part of the core to which the coil is not wound.
With the configuration of the related art that attaches an end cap to both ends of the laminated core part of the antenna as described in Japanese Unexamined Patent Appl. Pub. JP-A-2005-269234, the end caps increase the size of the timepiece module accordingly and interfere with forming the timepiece thinner and smaller.
Furthermore, a problem with the configuration that affixes an amorphous thin film to the core as described in Japanese Unexamined Patent Appl. Pub. JP-A-2007-184894 is that the amorphous thin film becomes easily damaged when shock is applied to the timepiece. Damage to the thin film can be prevented by additionally providing a support member, but providing such a support member also increases the size of the timepiece.